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2005-2006AP Biology
Lipids Lipids are composed of C, H, O
long hydrocarbon chain Diverse group
fats phospholipids steroids
Do not form polymers big molecules made of
subunit smaller molecules not a continuing chain
2005-2006AP Biology
Fats Structure:
glycerol (3C alcohol) + fatty acid
dehydration synthesis
fatty acid = long HC “tail” with COOH group at “head”
2005-2006AP Biology
Fat Triacylglycerol
3 fatty acids linked to glycerol ester linkage = between OH & COOH
2005-2006AP Biology
Fats Long HC chain
polar or non-polar? hydrophilic or hydrophobic?
Function: energy storage
very rich 2x carbohydrates
cushion organs insulates body
think whale blubber!
“Let’s go to the video tape!”(play movie here)
2005-2006AP Biology
Saturated fats All C bonded to H No C=C double bonds
long, straight chain most animal fats solid at room temp.
contributes to cardiovascular disease (atherosclerosis) = plaque deposits
2005-2006AP Biology
Unsaturated fats C=C double bonds in the fatty acids
plant & fish fats vegetable oils liquid at room
temperature the kinks made by
double bonded C prevent the molecules from packing tightlytogether
2005-2006AP Biology
Phospholipids Structure:
glycerol + 2 fatty acids + PO4
PO4 negatively charged
other small molecules may also be attached
adenine (ATP)
2005-2006AP Biology
Phospholipids Hydrophobic or hydrophilic?
fatty acid tails = hydrophobic PO4 = hydrophilic head dual “personality”
interaction with H2O is complex
& very important!
2005-2006AP Biology
Phospholipids in water Hydrophilic heads attracted to H2O
Hydrophobic tails “hide” from H2O self-assemble into aggregates
micelle liposome early evolutionary stage of cell?
2005-2006AP Biology
Why is this important? Phospholipids define outside vs. inside Where do we find phospholipids in cells?
cell membranes
2005-2006AP Biology
Phospholipids & cells Phospholipids of cell membrane
double layer = bilayer hydrophilic heads on outside
in contact with aqueous solution hydrophobic tails on inside
form core forms barrier between cell &
external environment
2005-2006AP Biology
Steroids ex: cholesterol, sex hormones 4 fused C rings
different steroids created by attaching different functional groups to rings
cholesterol
2005-2006AP Biology
Cholesterol Important cell component
animal cell membranes precursor of all other steroids
including vertebrate sex hormones high levels in blood may contribute to
cardiovascular disease